1. Field of the Invention
The invention relates to an electric heating means and particularly to a multi-layer, electrical film heater in strip form having an improved terminal means.
2. Description of the Prior Art
A solid plate surface heating unit design with a multi-layer, thin film heater in strip form bonded to the underside of a high silica glass plate is described in an earlier patent of the present inventor, U.S. Pat. No. 3,067,315, which is also assigned to the same assignee as is the present invention. This patent shows the film heater terminals located on a down-turned tongue portion near the peripheral edge of the plate beneath a reflector pan so as to be remote and shielded from the main heated portion of the film heater and to create a large temperature drop of several hundred degrees Fahrenheit between the heated portion and the terminals.
Another solid plate surface heating unit design with an electrical film heater is shown in the Brouneus U.S. Pat. No. 3,813,520. This film heater design includes a pair of metallic thin film terminals of a low electrical resistance material.
The principal object of the present invention is to provide an electrical thin film heater of noble metals with diffusion barrier means interposed between the main portion of the film heater and its electrodes.
A further object of the present invention is to provide a solid plate surface heating unit with a high temperature film heater of noble metals and barrier means to prevent electromigration between dissimilar noble metals at the separation plane of the electrode.